Dynamic retinoscopy is used to objectively determine a patient's refractive error when their accommodation is active. It involves having the patient fixate on a near target while the examiner performs retinoscopy. The direction of the retinoscopic reflex indicates whether the eye is focused in front of, behind, or aligned with the retinoscope. Various methods of dynamic retinoscopy have been developed, including Monocular Estimation Method, Bell retinoscopy, and Nott retinoscopy. Dynamic retinoscopy can reveal a patient's lag of accommodation, or the difference between their accommodative response and the stimulus provided by the near target. A normal lag is between +0.50D to +0.75D.

1. DYNAMIC
RETINOSCOPY
Srijana lamichhane
B.optom,IOM (MMC)

2. What is retinoscope ?
 Is an instrument used to determine the refractive error
 Is an objective method
What is retinoscopy ?
 The purpose of retinoscopy is to obtain an objective
measurement of patient’s refractive state
 it is based on the fact that when the light is reflected from a
mirror into the eye, the direction in which the light will travel
across the pupil will depend upon the refractive state of the
eye

3. Types of retinoscopy
 static retinoscopy: the patient is looking at a
distance object, with accommodation relaxed
 Dynamic retinoscopy: the patient is looking at a
near object ,with accommodation active
 near retinoscopy: the patients is looking at a near
object, with accommodation relaxed

4. Dynamic retinoscopy
 Objectively determines the point that is conjugate to
the retina when the pt. is viewing a particular target
 NO WORKING DISTANCE POWER IS ADDED OR
SUBSTRACTED FROM THE FINDING

5. Movements
same as that of static retinoscopy
 With movement : eye conjugate to a point either
behind the eye or behind the retinoscope.
 Against movement : eye conjugate to a point
between the eye (patient’s) and retinoscope.
 Neutrality : eye conjugate with retinoscope

6. History
 early 1900s, various investigators began utilizing the
retinoscope to determine the amplitude or status of
accommodation in non-verbal patients - term dynamic
retinoscope emerged
 A.J. Cross is credited with introducing the basic theory
and method for dynamic retinoscopy
 Sheard, Nott, and Skeffington - elaborated on the
theory and procedure

7. Goals
 to determine accommodative Response
 also helped to determine the most appropriate near
prescription with testing conditions
 Reveals the degree to which accommodation is
fluctuating when attending to a near target & if the
eyes are balanced equally at near
 provide the information and insights regarding the
patient’s abilities and level of visual processing at the
chosen distance

8. Accomodation
 Accomodative stimulus is defined by the near target
stimulus
 Because of depth of focus and depth of field the
accommodative response is generally less than the
stimulus
 Near point is usually located around 10-17cm
beyond near target at 40cm

9. Accommodation
 Accomodative demand is provided by the target
distance as well as the refractive error
 Over minus or under plussed: has extra accommodative
demand required to see target clearly
 Under minused :does not have to accommodate as
much

10. Accommodation
 Accommodative response is a measure of the actual
accommodation that is present
If your accommodative system likes to “hang out”
Right on the target accommodative
response = stimulus
In front of the target accommodative
response >stimulus (i.e. accommodative lead)

Behind the target accommodative
response< stimulus ( i.e.accommodative lag)


11. Types of dynamic retinoscopy
Monocular Estimation Method (MEM)
Nott retinoscopy
Bell retinoscopy

12. MEM (monocular estimated method)
 Founder Dr. Harold Haynes
 Clinician neutralize the reflex of the eye while patient
accommodates to fixate a target placed at the
patient’s customary reading distance (usually at 40cm)

13. Materials
 series of cards with a central aperture mounted on
a retinoscope
 cards can have printed letters, or words, or pictures
that range in size from 20/160 (6/120) to 20/30 (6/9)
 Arranged around the aperture

15. Procedures
 instructed to keep the targets clear
 sweeps the retinoscope beam
 observes the motion of the retinoscopic reflex
 quickly interposes a trial lens at the spectacle plane

16. Interpretation
 “lag of accommodation” is the amount of plus lens
that neutralizes the reflex
 has been found to accurately measure the lag of
accommodation in an objective manner
Example
If the retinoscopic reflex is neutralized by +1.75D then
lag is
ADD = +1.75 – (+0.75)
= +1.00

17. Limitation
 Plus lenses – relaxation of accommodation –
accommodative response measured by this value
found to be 10% less
 No longer than one fifth of a second

18. Bell retinoscopy
 Developed by Drs. W.R. Henry and R.J. Appel
 Evaluate the performance of the accommodative
system under moving & real life conditions in free space
 cognitive demand is low
 term “Bell” is used because the procedure was done
originally using a cat-bell suspended on a string.

19. Materials
 Three dimensional viewing target
 a small, highly reflective bell dangling from String –
replaced with a Wolff Wand(½ inch diameter, metal
ball mounted on the end of a rod)

20. Procedures
 wand is held by the examiner
 moved closer to and farther from the patient -
slower than 2 inches/sec
 retinoscope is positioned at a fixed distance of 50
cm (20 inches)
 patient fixates the target and the examiner notes the
direction of the reflex

21. Contd
 target is moved closer to the patient there will be a
point where the motion changes from “with”
to“against’’
 Target is again moved away from patient until with
motion is observed

22. Interpretation
 The two measurements are recorded as a fraction e.g.
30/40 (meaning that the inward change from “with”
to “against” occurred at 30cm and the outward
change from “against” to “with” occurred at 40cm.
 The expected values for Bell retinoscopy are: Inward
shift at 42.5 to 35cm and outward shift at 37.5 to
45cm.
 If the lag of accommodation does not fall within
these ranges, the procedure is repeated with plus
lenses. Lenses which normalize these ranges are
considered an acceptable nearpoint prescription.

23. Contd
 eye movement control can be assessed by judging
the extent to which the ball can be fixated
 eye-hand coordination can be evaluated by asking
the patient to touch the Wolff Ball during the
procedure
 NPC can be determined by the normal means
limitation
 patient converges - scoping more off axis

24. Nott’s retinoscopy
 developed by I. S. Nott in the 1920s
 main purpose is identical to the MEM method
 cognitive demand is moderate

25. materials
 reduced block of 20/20 (6/6) letters is
placed at 16 inches (40 cm) from the patient

26. Procedures
 Patient wearing their best correction is instructed to
view a detailed and high contrast target placed on
the retinoscope
 Retinoscopic reflex is examined from the plane of
target and retinoscope is moved closer or farther
away from the target until neutrality is achieved

27. Interpretation
 Dioptric difference between these two distances
equals the lag of accommodation
Example
Distance from the target to spectacle plane = 40cm
Distance from retinoscope to spectacle plane = 50cm
Lag of accommodation = +2.50D – 2.00D
= +0.50D

28. Book retinoscopy
 Also known as getman retinoscopy.
 Developed at gesell institute of child
development at yale university.
 Develop to obtain information about
the visual processing of nonverbal
infants .
 Cognitive demand is high.

29.  Getman and kephart described the following
response levels with this technique.
A. free reading level : Desirable , reflex varies from
neutral to with
B. Instructional level : more demanding than the free
reading level , reflex is a varying fast against motion. •
C. Frustration level : Even though the subject is
“focused” on the page he is not interpreting the
information properly slow against motion
 Reflex color is bright and white when the words are
understood.

30. Contd
 Reflex color is more pink and dims slightly if the
patient is struggling to comprehend a word or
passage.
 Reflex color is dull and brick colored when the patient
has given up on comprehending a word or reading
passage.

31. Cross retinoscopy
 Andrew J. Cross (1911) •
 Start with static retinoscopy finding .
 Patient made to view target at 40cm .
 Examiner performs retinoscopy adding plus lens till
neutrality.
 A alternative to cycloplegic refraction
 Method of adding plus lens power to obtain a
reversal

32.  Determining the correction in cases of
Astigmatism
Presbyopia
Subnormal accommodation in young patients

33. Limitation
 A measurement of negative relative accommodation
 Plus power recommended – patient would not persist

34. Sheard’s method
 Charles Sheard (1920)
 Introduced the concept of “ Lag of accommodation”
 add plus lens power until neutrality occurred

35. Tait’s method
 Tait(1953)
 Working distance = 33cm
 Fogging with a considerable amount of plus lens
power and then approaches neutral by reducing the
plus lens power
 Found an average of approximately +1.50 D more
than sheard system , thus total lag of accommodation
= +2.25 D
 Close to +2.50D i.e Negative relative accommodation.

36. low neutral and high neutral methods
Sheard ( low neutral method)
 The end point is the least plus power required for a
neutral reflex to be observed.
Cross ( high neutral method)
 Addition of plus power beyond neutrality until a
reversal occurs.

37. Stress point retinoscopy
 developed by Harmon and Kraskin
 evaluate the response of the entire organism to stress
 in stress-point retnoscopy - looking at the change in
reflex quality
 Cognitive demand is moderate to high

38.  reasoning behind stress-point retinoscopy is that
vision is intimately related to the whole body and
that a physiological change in stress occurring in the
body can be perceived through a change in the
retinal reflex
 Three things occur when near-point stress is
experienced
 Firstly - there is a change in the individual's pulse
 Secondly - there is an inner canthal twitch and
 lastly - change in the colour of the retinal reflex is
observed

39. Procedures
 Wolff ball is moved closer to the patient - looks at
which distance the reflex "pops"
 initially brightened and then became dull and finally
brightened again - termed "popping" of the reflex -
about 4 inches in front of the patient
 distance is noted and then different lenses are placed
binocularly and the procedure is repeated

40.  ideal lens is the one which makes the stress point as
close to the subject as possible
 more desirable to have the stress-point closer to the
patient - they are not working under physiological
stress
 For example; if the stress-point of a subject is 40cm
and they habitually read at 30cm they would be under
constant near-point stress

41.  plus lenses move the stress-point
closer to the subject and minus lenses
move it away
 in children the stress-point should be
10cm closer to the subject than the
Harmon distance.
 In adults, the stress point is 20 to
22.5cms from face.

42. Near retinoscopy by mohindra
 Near retinoscopy by mohindra in 1977.
 For use in determining the refractive state of infants
and children
 The stimulus or fixation is the dimmed light source
of the retinoscope in a darkened room.
 The retinoscope is held at a distance of 50 cm with
hand-held trial lenses.

43.  Near retinoscopy differs from other forms of dynamic
retinoscopy in the following ways:
1. it is performed in complete darkness , the only
illumination in the room is supplied by retinoscope
with child fixating at retinoscope light .
2. It is monocular procedure that is eye not being
examined is occluded.
3. The adjustment factor of -1.25 D is algebrically
combined with the spherical component of the gross
sphero - cylindrical lens powers.

44. Contd

45. Lag of accommodation
 Time lapse between the presentation of an
accommodative stimulus and occurrence of the
accommodative response
 Average time
 - Far to near accommodation is 0.64 seconds
 - Near to far accommodation is 0.56 seconds

46. Lag of accommodation
 Accommodative lag = accommodative demand (
+2.50D at 40 cm) – accommodative response
 Lags are greater when closer test distances are used
 Lag of accommodation exhibits a slow but
progressive increase to adult levels
 Binocular accommodative system normally respond
with only +1.75D to +2.00D of increased plus power

47.  Normal Lag: +0.50 or +0.75 diopters
 High Lag: +1.00 diopters or higher
 Lead : +0.25 diopters or less

48. Lag > +0.75D/ High Lag
 Inadequate accommodative response:-
 as a result of :- near esophoria
poor negative vergences
accommodative insufficiency
uncorrected hyperopia
Patient is Overminused

49. Low Lag /lead of accommodation <
+0.50
 Overaccommodating
 As a result of :- near exophoria
spasm of accommodation
Over Plus Correction
inadequate positive vergences

51. Source of error
Same as those with static: scissors, small pupils,
dim media (cataracts, etc.), angle
More sensitive to physical arrangement for the
measurement (distance, lens adaptation),
instructions given and patient’s cooperation
 Changes in patient’s fixation or accommodative level
(often related to failure to understand task or to
cooperate)

52. Patient looking at a target at a different distance
than requested
A +0.50 to +0.75 lag is not normal if not testing
at 40cm
Lag increases as fixation distance is reduced
Adaptation to lenses with MEM: relaxes with plus
lenses, stimulates with minus lenses

53. Refrences
o Clinical Procedures in Optometry by J.D. Bartlett, J.B.
Eskridge, J.F. Amos
o Theory and Practice of Squint and Orthoptics by
A.K.Khurana
o Borish’s Clinical Refraction by W.J. Benjamin
o Internet